| The oxidation behaviors of Co-Ni hydroxide coprecipitates were investigated with relation to the conditions of the solution such as R value(=2〔OH^-〕 / 〔SO^(2-)₄〕), temperature and initial 〔Ni(Ⅱ)〕/〔Co(Ⅱ)〕 molar ratio. The characteristics of reaction products were examined by composition analysis, XRD, TEM and magnetic property measurement. When increasing R value, the reaction time and particle sizes were increased. And the reaction products were Co-Ni ferrite. The amount of Co incorporated into the spinel structure increased and that of Ni decreased with increasing R value and temperature. In reaction products represented by Co, Ni_yFe_(3-(x+y))O₄, the amount of (x+y) shows the ranges between 0.6 and 0.7, regardless of R value and temperature. In the conditions of R=1.5, 70℃, 〔Co(Ⅱ)+Ni(Ⅱ)〕/〔Fe(Ⅱ)〕 ratio 0.5, 〔Ni(Ⅱ)〕/〔Co(Ⅱ)〕 ratio =2.0 in the initial solution, Co and Ni incorporated with equal amounts into spinel structures and the reaction product of Co_(0.29)Ni_(0.29)Fe_(2.41)O₄ was obtained. |
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